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December pattern/forecast thread


weathafella

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29 minutes ago, Googlymoogly said:

What do the other models show? Don't models tend to rush this stuff? And how AN does it look?

They show the same thing, but it's still not a PAC jet furnace.  The models always rush these things..it's usually a bias. But a bias of a day or two vs a week....tough to say. It's probably fluctuations with the tropical Pacific and how they are handling the convection and associated Rossy Wave train. No need to panic.  Hopefully we can cash in on an event or two in the next two weeks...but remember these patterns also favor cyclogenesis in the Plains so we may still deal with storms cutting west of us. I only say this so we don't hear whining.  It's close to an all out snow blitz here, or congrats Midwest. 

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14 minutes ago, CoastalWx said:

They show the same thing, but it's still not a PAC jet furnace.  The models always rush these things..it's usually a bias. But a bias of a day or two vs a week....tough to say. It's probably fluctuations with the tropical Pacific and how they are handling the convection and associated Rossy Wave train. No need to panic.  Hopefully we can cash in on an event or two in the next two weeks...but remember these patterns also favor cyclogenesis in the Plains so we may still deal with storms cutting west of us. I only say this so we don't hear whining.  It's close to an all out snow blitz here, or congrats Midwest. 

We typically need a pretty stout west NAO block in conjunction with some favorable PAC variables to avoid riding the line in December...and it's pretty rare. Dec 1995 is an example and so is Dec 1976. 

 

Otherwise we're probably playing with fire. But that's the way it is in December usually with the PJ still a bit more poleward than in Jan and Feb. 

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23 minutes ago, CoastalWx said:

They show the same thing, but it's still not a PAC jet furnace.  The models always rush these things..it's usually a bias. But a bias of a day or two vs a week....tough to say. It's probably fluctuations with the tropical Pacific and how they are handling the convection and associated Rossy Wave train. No need to panic.  Hopefully we can cash in on an event or two in the next two weeks...but remember these patterns also favor cyclogenesis in the Plains so we may still deal with storms cutting west of us. I only say this so we don't hear whining.  It's close to an all out snow blitz here, or congrats Midwest. 

Thanks Scott. Totally not panicking, just trying to get a grasp on the meaning of it all. It would be dope to avoid a grinch this year, but I'm looking forward to the wintry midsection of the month that seems to be shaping up. 

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17 minutes ago, 40/70 Benchmark said:

I don't buy a flip back ro garbage that quickly, grinch events not withstanding....Should be a fun stretch around the turn of the month.

I didn't view it as a flip...just something to keep an eye on. I hope we can cash in on an event or two. Tenuous setup with the trough out in the Plains. We play with fire. 

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2 hours ago, CoastalWx said:

I didn't view it as a flip...just something to keep an eye on. I hope we can cash in on an event or two. Tenuous setup with the trough out in the Plains. We play with fire. 

Arguably the first ensemble to out of the box at 12Z backs off of what last nights ensembles were showing.

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2 hours ago, CoastalWx said:

GEFS rebuilt AK ridge again. That's all I really care about. Seems like a 12z and 00z ebb and flow going on lately.

EC ensembles look better at 12z too. More ridging in Greenland and heights higher in AK than 00z run. 

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1 hour ago, ORH_wxman said:

EC ensembles look better at 12z too. More ridging in Greenland and heights higher in AK than 00z run. 

 

What will be the mechanism to induce -NAO formation, however? I have seen this occur numerous times already this fall with respect to spurious geopotential height rises progged near Greenland -- more of an issue with the GEFS. 

Notice also in the medium term, heights have gradually corrected higher along the East Coast. The pattern overall is a terrible one for the coast through mid month at least, and especially NYC southward. Tropical forcing and stratospheric evolution are not conducive for protracted blocking in the NAO/AO domains. Hopefully we see subsequent wave 1/2 attacks, but at this time, zonal winds from 150hpa up through 10hpa are progged near or above normal by D7.

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2 hours ago, Damage In Tolland said:

Lots of false alarm worried panic attacks this morning. Things have and continue to look promising 

Things look serviceable, but I see nothing to be overly excited about.

We've been living in the extended range for 2-3 weeks.

 

Nothing to complain about, but I wouldn't do handstands, either.

Not saying you were-

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6 minutes ago, 40/70 Benchmark said:

Things look serviceable, but I see nothing to be overly excited about.

We've been living in the extended range for 2-3 weeks.

 

Nothing to complain about, but I wouldn't do handstands, either.

Not saying you were-

It's hard to go full nudity in early/mid December. So yeah...about as good as we can hope for this early in the season outside of some fantasy 570dm block over the Davis Strait with a PNA ridge centered over Boise ID.

2 hours ago, Isotherm said:

 

What will be the mechanism to induce -NAO formation, however? I have seen this occur numerous times already this fall with respect to spurious geopotential height rises progged near Greenland -- more of an issue with the GEFS. 

Notice also in the medium term, heights have gradually corrected higher along the East Coast. The pattern overall is a terrible one for the coast through mid month at least, and especially NYC southward. Tropical forcing and stratospheric evolution are not conducive for protracted blocking in the NAO/AO domains. Hopefully we see subsequent wave 1/2 attacks, but at this time, zonal winds from 150hpa up through 10hpa are progged near or above normal by D7.

I dunno, it's clearly trying to wave-break using the storm threat around Dec 14/15 as the catalyst...who knows if it happens. It would be a luxury anyway for New England...we can try and work with the serviceable PAC which looked better this run at the end vs 00z. 

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6 minutes ago, 40/70 Benchmark said:

Fair enough, Will.

I do agree with the fact that its nothing to complain about.

I wasn't really disagreeing with you. I wouldn't do handstands either. It's got some good potential but it isn't this infallible setup. I don't think we'd be shocked if we pulled a 1980s. We'll probably do better but it's definitely one scenario. 

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on the fence...

the flow's too fast - that factor alone cancels out a lot of mechanics of s/w/ forcing.  until that alleviates ...i don't see much changing... mid and extended range tease fests that end up like tomorrow's deal or not at all.

on the other side, several GFS members still like the 9th through 15th with several members showing eastern amplitude riding if not bouncing over top..

flow too fast isn't an absolute limitation and that's the rub... it just makes it maddening and dicey, with misses at a surplus too

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4 minutes ago, Typhoon Tip said:

on the fence...

the flow's too fast - that factor alone cancels out a lot of mechanics of s/w/ forcing.  until that alleviates ...i don't see much changing... mid and extended range tease fests that end up like tomorrow's deal or not at all.

on the other side, several GFS members still like the 9th through 15th with several members showing eastern amplitude riding if not bouncing over top..

flow too fast isn't an absolute limitation and that's the rub... it just makes it maddening and dicey, with misses at a surplus too

Good post...that is the way I see it.

It's not a high probability pattern, but it isn't prohibitive, either.

We wait-

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After last December's disaster I would definitely role the dice with this pattern.  Like others alluded to, no real pronounced + PNAP western ridge structure or highly anomalous blocking,  the Teles are a bit flatter and the flow a bit faster  than optimum, some latitude and elevation definitely could help but it's all about wave spacing, constructive/deconstructive interference and all kinds of small scale features and nuances.  At least we are not staring down the barrel of a massive torch like last December.  If I get a couple lighter 1-3 type events and perhaps throw in one more moderate or significant event like 4-6+ by Christmas I would sign for it here in the valley .  

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13 minutes ago, Googlymoogly said:

hows the LR looking after last night? Ed Vallee on twitter says it's a spread on guidance...but that he leans warm after the 20th. 

I don't think anything changed. Usually you aren't gonna get drastic changes from one run to another.....well at least to sway someone's thinking anyways. You look for trends. The longer range stuff such as weeklies from euro and cfs do warm us up after the 20th or so. We shall see. The euro ensembles actually were rather cold in the 11-15 day.

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13 minutes ago, CoastalWx said:

I don't think anything changed. Usually you aren't gonna get drastic changes from one run to another.....well at least to sway someone's thinking anyways. You look for trends. The longer range stuff such as weeklies from euro and cfs do warm us up after the 20th or so. We shall see. The euro ensembles actually were rather cold in the 11-15 day.

cool. feels like some mets enjoy squashing/condescending to weenies. as long as its a moderation and not a torch I don't see any reason to tell snow lovers to hold their excitement. first Dec like this in a long time and I for one am happy about it.

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